Process for producing artificial threads, fibers, and the like



Patented Dec. 7, 1937 UNITED STATES PROCESS FOR PRODUCING ARTIFICIAL THREADS, FIBERS, AND THE LIKE Martin Giinther and Johann Eggert, Berlin, Germany, assignors to Patentverwertung Dr. Martin Giinther G. in. b.

11., Berlin, Germany, a

corporation of Germany No Drawing. Application October 19, 1935, Se-

rial No. 45,831.

6 Claims.

This invention relates to a process for disintegrating or solving vegetable substances such as straw cellulose with a view to form them by known methods to fibrous or other products.

It has already been proposed to produce by the socalled viscose-process artificial threads from Wood which has been disintegrated to sulphite cellulose. It is also known to reduce cotton or cotton linters to viscose which latter may be spun.

In addition to these vegetable substances, most of the other kinds of plants, particularly those of annual growth, such as alfa-grass, broom, hemp, flax, Indian corn, corn-straw and others, contain more or less considerable quantities of cellulose. The word corn-straw employed herein refers to the straw of the small grains.

Up to now, artificial threads have not been spun from cellulose solutions containing straw cellulose; the cellulose obtained from the above 20 plants has been little used in the manufacture of paper, because, especially in the case of cornstraw, the cellulose could not be obtained in the sufiiciently pure condition as required for dissolving the cellulose by the viscose-process and subsequently forming it in accordance with the viscose-spinning method to artificial threads and other similar products. Besides, the yield of pure cellulose was too low, while, with increased yield, an incomplete disintegration was unavoidable. 30 If, for instance, corn-straw be treated with alkaline solutions, even under pressure, a cellulose will be obtained which is little adapted for the production of, say, artificial threads. It can be assumed that this effect is due to the fact that 35 in the presence of silicic acid an ingredient of the corn-straw and also other substances included therein will only be incompletely disintegrated under the action of alkali. If, in such a process, the pressure be enhanced or the addition of 40 chemicals be enlarged, an improper disintegrated cellulose will be obtained.

It is an object of this invention to overcome these difiiculties and to solve or reduce strawcellulose, for instance, in such a manner that it 45 may be formed by known methods into threads or other products.

More particularly the invention consists in preboiling corn-straw under 4-10 atmospheres in a boiling lye or wash which is taken from the final o boiling of the said substance. Such a lye which has already been used once, is still slightly alkaline if the process be effected with alkali; it, however, contains large quantities of organic substances of the disintegrated material. The said 55 substances are apparently able to loosen the cel- In Germany October 20, 1934 lulose fibers embedded within the corn-straw so that small quantities of alkali. or alkaline substances of organic or inorganic nature will be sufficient to disintegrate by a second boiling the cellulose fibers in a remarkable purity.

The preboiled corn-straw may, with advantage, be steamed under pressure before the final boiling; the latter can then be effected with fresh alkali, reducing substances being eventually added.

An example of the inventive process is as follows: 25 kg. straw are boiled during 1-2 hours and under a pressure of 4-10 atmospheres together with 100 liters of a lye which has already been used. After that, the liquid is removed, while the straw is steamed during l-2 hours and under 4-10 atmospheres in order to loosen the partially disintegrated fibers. After the steaming process, any condensing liquid, if present, is removed whereupon the final boiling is effected with a slightly alkaline solution containing about 4% sodium hydroxide; this step extends over approximately 4 hours and under 4-10 atmospheres. Thereafter, the lye is drawn off and used again for preboiling purposes.

The described treatment results in a considerable yield of cellulose which may easily be worked, particularly spun, according to the viscose process. A further advantage of the novel method consists in that with a cellulose obtained by the inventive process a portion only of the usually required bleaching means, such as a chlorine-solution, is necessary which means must otherwise be applied in a rather concentrated condition.

We claim as our invention:

1. In a process for disintegrating straw containing cellulose, the continuous steps of preboiling corn straw under a pressure from 4 to 10 atmospheres with a previously used alkaline lye, of steaming the preboiled straw under pressure after a removal of the lye, of after-boiling the straw with a fresh alkali and of employing the alkali of said after-boiling for preboiling a further quantity of corn straw.

2. A process for the manufacture of cellulose from straw which comprises preboiling the straw under pressure with an alkali solution previously used in final treatment of other straw, draining ofi the alkali solution, steaming the preboiled straw under pressure, draining off condensing liquid, finally boiling the preboiled and steamed straw under pressure with a solution of fresh alkali, and drawing off the last named solution for use in pretreating another quantity of straw.

3. In a process for the manufacture of cellulose from straw which includes preboiling and final boiling steps with alkali, the step which comprises preboiling the straw of one batch with the alkali used in the final boiling step of a previous batch of straw.

4. In a process fol the manufacture of cellulose from straw which includes preboiling and final boiling steps with alkali, the step of using a fresh alkali solution in the final boiling of one batch of straw, draining off said alkali solution, and preboiling the next batch of straw with said alkali solution previously used in the final boiling step of said one batch of straw.

5. A process for the manufacture of cellulose from straw which comprises preboiling the straw between 1 and 2 hours under a pressure of from 4 to 10 atmospheres with an alkali solution previously used in final treatment of another batch of straw, draining off and discarding said alkali solution, steaming the preboiled straw between 1 and 2 hours under a pressure of from 4 to 10 atmospheres, removing any condensate formed, finally boiling the preboiled and steamed straw for approximately 4 hours at 4 to 10 atmospheres pressure with a fresh alkali solution, and removing said fresh alkali solution after the boiling for use in preboiling a subsequent batch of straw. 6. A process for the manufacture of cellulose from straw which comprises preboiling one batch of straw with alkali used in finally boiling a previous batch, finally boiling the preboiled straw with a fresh alkali solution containing reducing substances, and removing said fresh alkali solution thereafter for use in preboiling a subsequent batch of straw.

MARTIN GI'JNTHER.

J OHANN EGGERT. 

